In June 2007, clinicians and scientists working on rare diseases caused by abnormal sterol metabolism organized a conference (Smith-Lemli-Opitz Syndrome and Inborn Errors of Cholesterol Synthesis) in Portland, OR. Since then, much progress has been made in the field of sterols and rare diseases so as to warrant another conference that will bring together scientists, clinical investigators, trainees and families. The overall objective of the proposed conference is to integrate the most up-to-date information from various research disciplines relevant to SLOS and help define future research directions. The major topics that will be covered during the conference include: 1) rare diseases caused by abnormal sterol metabolism; 2) role of sterols in embryonic development and central nervous system function; 3) pathogenesis of SLOS and other sterol-related genetic diseases; 4) relevant animal and cellular disease models; 5) from genotype to phenotype; and 6) perspective on therapeutics. The proceedings of the Conference will be published in a peer-reviewed journal. The 2013 SLOS Scientific Conference will be held in June 2013 in Pittsburgh, PA. The Conference will be in the form of a symposium with significant time allocated for discussion periods following introductory and scientific talks. National and international experts in relevant fields will be invited. Young scientists and trainees will be encouraged to attend and present their work at a poster session. Travel awards will be made based on meritorious abstract submissions. Importantly, the Conference will be held in conjunction with the SLO/RSH Family and Medical biannual meeting. A Q & A session will be organized the agenda will allow several opportunities for direct interactions between families and scientists.